Liquid fuel burners



July 11, 1961 R. E. ZOLLER LIQUID FUEL BURNERS Filed Maroh 20, 1959 pmWM WW mm m INVENTOR. Ronald E. Ziiller ATTORNEY United States Patent g y2,991,941 LIQUID FUEL BURNERS Ronald E. Zoller, London, England,assignor to Babcock 8: Wilcox, Limited, London, England, a company ofGreat Britain Filed Mar. 20, 1959, Ser. No. 800,797 Claims. (Cl.239-426) This invention relates to liquid fuel burners and to a methodof generating heat at a variable rate. More specifically, the inventionrelates to liquid fuel burners of the kind having a whirl chamber with adischarge orifice for the passage from the whirl chamber of whirlingfuel. Various modes of regulating the output of such burners have beenadopted in the past. For example, according to one mode the output of aburner is varied by regulating the pressure at which the fuel issupplied to the burner. However, such regulation is suitable only for alimited range of output since reduction in pressure tends adversely toeffect fineness of the spray, and therefore leads to deterioration inthe combustion process. According to another mode a variable proportionof fuel is returned from the whirl chamber to the fuel supply system.Whilst with this method a fine spray may be obtained over a wide rangeof output, the regulation is accompanied by a relatively great variationin the spray cone angle and this variation is liable to lead todifliculties.

The invention provides an improved means for regulating rate of firing,and an improved method of generating heat at a variable rate by means ofa burner of the kind described.

In a liquid fuel burner of the kind specified in accordance with thepresent invention, beyond the orifice is an interceptor adapted tointercept a variable proportion of the cone of spray projected from theorifice and to direct the intercepted fuel towards collecting means.

The invention also includes a method of generating heat at a variablerate by combustion of liquid fuel delivered by a burner of the kindhaving a whirl chamber with a discharge orifice for the passage from thewhirl chamber of whirling fuel, according to which at least over a partof the range of heat demand a proportion of the cone of spray dischargedfrom the orifice is intercepted and led to collecting means and theproportion is varied in order to satisfy the demand for heat.

In one embodiment of the invention, the interceptor is formed, for thepassage of spray to a combustion space, with an aperture co-axial withthe whirl chamber and adapted to determine the proportion of the cone ofspray which reaches the combustion space.

Generally, the aperture will be circular, although by choice of theshape of the aperture, the form of that part of the cone of spray whichpasses the aperture, and therefore the flame shape, may be controlled.By way of example, by the use of an oval aperture of suitable dimensionsa flame of transverse dimensions in one direction greater than itstransverse dimensions in a direction at right angles to the firstdirection may be produced.

The invention further includes a liquid fuel burner of the kind having awhirl chamber with a discharge orifice for the passage from the whirlchamber of whirling fuel, wherein beyond said orifice is a member whichforms a wall of a chamber around the orifice, and an aperture alignedwith said orifice is provided in said wall for passage therethrough offuel from said aperture, and means are provided for effecting relativemovement between said wall and said orifice to vary the proportion offuel from said orifice which passes through said opening.

An embodiment of the invention will now be described,

ice

by way of example, with reference to the accompanying drawing, in which:

dFIG. 1 is a sectional elevation of a liquid fuel burner, an

FIG. 2 is a section on the line 11-11 of FIG. 1.

Referring to the drawing, the burner which may be used in firing acombustion space, e.g., that of a steam generator, includes a barrel orfuel conduit 10 into which liquid fuel at suitable temperature issupplied in a conventional manner through inlet 11. A whirl chamber 12at the discharge end of the barrel 10 has a discharge orifice 13 whichis formed as a recess or opening in sprayer plate 14. Fuel from barrel10 passes to chamber 12 thrugh a spacer or distributor plate 15 whichforms the rear wall of chamber 12.

Surrounding the barrel 10 is a housing or casing including an outerbarrel 16 and an end member or a front cap 17 of cylindrical form whichis screwed onto the front end of the barrel 16. The member 17 is formedwith an annular end wall 18 which constitutes an interceptor having thecenter of its circular aperture 19 on the axis of the barrel. The member17 and the sprayer plate 14 are relatively movable by control means 20in order that the member 17 may intercept variable portions of the fueldischarged from the whirl chamber. Fuel caught by end wall 18 is trappedin the chamber 17A within the member 17 and flows along the annularchannel between barrels 10 and 16 to outlet 21 wherefrom it is returnedto the fuel supply system of the burner.

The sprayer plate 14 and the spacer or distributor plate 15 arepositioned between a flanged outer sleeve 22 and an inner sleeve 23. Theinner sleeve fits closely around reduced end portion 24 of the barrel 10and is welded to this barrel as shown at 25. The outer sleeve 22 isscrewed on to sleeve 23 to clamp the plates 14 and 15 in position. Thedischarge end of the barrel portion 24 is spaced from the plate :15 toprovide a passageway for fuel from barrel 10. Plate 15 is formed with arear annular recess 26 and a front annular recess 27, and a series ofeight cylindrical passages 28 extend between the two recesses so thatfuel from barrel 10 may pass to the front recess 27, wherefrom the fueldischarges approximately tangentially into the chamber 12 through aseries of four openings 29 which are formed by slots in the rear face ofthe sprayer plate 14. The sleeve 22 is a sliding fit within member 17and is formed with a series of six channels 30 for flow of interceptedfuel to the annular channel between barrels 10 and 16. Member 17 isformed with a series of six fiat portions 31 which allow the end memberto be turned by a spanner or the like.

The control means 20 includes an externally graduated end or rear cap 32mounted on an externally screwthreaded portion of a body member 33 whichis screwed onto and forms the end of the outer barrel 16'. Radial arms34 are fixed to the cap 32 to facilitate manual rotation of the cap. Thebarrel 10 extends through the member 33 and an end piece 35 is securedto the rear end of the barrel by means of a stud 36 and nut 37 so thatthe end is sealed in a fluid-tight manner. A stud 38 is adjustablysecured in cap 32 to engage stud 36 so that rotation of cap 32 willeffect axial movement of the inner barrel 10. A compartment 39 is formedin the member 33 between an annular flange 40 and an apertured plug 41which is fixed by screws to the member 33. Sealing rings 42 and 43 areprovided in the flange and plug, respectively, to render the compartmentfluid-tight.

The fuel inlet 11 opens into the compartment 39 and apertures 44 areformed in the barrel 10 for flow of fuel oil from inlet 11 to theinterior of the barrel 10. A helical compression spring 45 extendsbetween end piece 35 and plug 41 to urge the barrel 10 rearwardly. An

- 3 annular flange 46 is welded to the inner barrel forwardly of flange40 at a location beyond which the barrel 10 is reduced in outsidediameter. The flange 46 acts as a stop to limit rearward movement. ofthe barrel 10.

In operation of the burner, suitably heated fuel oil is pumped atconstant pressure through inlet 11 to the interior of barrel 10 fordischarge through orifice 13 after whirling in chamber 12. Due tocentrifugal force the fuel is discharged in a hollow cone 47 of finespray and, as can 'be seen from FIGURE 1, a substantial part of the coneis intercepted by the wall 18 when sprayer plate 14 is in the rearmostposition. The intercepted fuel is trapped between wall 18 and the sleeve22 and so is caused to flow rearwardly through channels 30 and throughthe annular channel between barrels 10 and 16 to outlet 21. From theoutlet 21 the fuel is pumped back to the fuel supply system at alocation between the fuel heater (not shown) and the inlet 11. Theremainder 48 of'the spray cone passes into the combustion chamber toburn and so generate heat.

As shown in the drawings, the barrel 10 carrying the sprayer plate 14 isin the extreme rearward position, i.e., the position in which themaximum proportion of fuel is intercepted by wall 18. To reduce theproportion of fuel intercepted the cap 32 is rotated to move the cap andthus the barrel 10 forwardly. It will be seen that as the sprayer plate14 moves towards the wall 18 the proportion of fuel intercepted isreduced, and, when the plate 14 engages the wall 18, substantially allthe fuel discharged from orifice 13 passes through opening 19. Thus, thewall 18 intercepts a variable annular outer portion of the spray cone 47and a variable portion 48 of thespray cone is discharged into thecombustion space. Since the radially outer portion of the spray cone inwhich the spray particles tend to be larger is intercepted, the averagespray particle size in that part of the cone passing through aperture 19tends to be relatively small. This is advantageous from the point ofview of combustion.

The diameters of the orifice 13 and the opening 19 are chosen to suitthe operational requirements of the burner. Although the aperture 19 isshown to be considerably larger than orifice 13 it has been foundsatisfactory to have aperture 19 only slightly larger than orifice 13.

While the instant invention has been disclosed with reference to aparticular embodiment thereof, it is to be appreciated that theinvention is not to be taken as limited to all of the details thereof asmodifications and variations thereof may be made without departing fromthe spirit or scope of the invention.

What is claimed is:

1. A liquid fuel burner comprising an elongated housing having opposedfront and rear open end portions, a conduit forming a fuel passagespatially disposed in and extending longitudinally of said housing, saidhousing and conduit being connected for relative movement, bearing meanssupporting said conduit within said housing, said bearing means dividingsaid housing into a fuel inlet compartment and a fuel outletcompartment, said housing having a fuel inlet communicating with saidinlet compartment and a fuel outlet in communication with said fueloutlet compartment, said conduit having an opening in communication withsaid fuel inlet compartment, an atomizing head connected to thedischarge end of said conduit, said head including means defining a fuelwhirl chamber terminating in an orifice for discharging the fueltherefrom in the form of a spray, a front cap member connected to thehousing to close the front end thereof, said cap having a wall portionprovided with an aperture therein spaced :from said atomizing head, saidaperture being substantially in co-axial alignment with said orifice,and means for adjusting said conduit axially of said housing, saidadjusting means including a rotatable rear cap member closing said rearend of the housing whereby a rotation of said rear cap causes acorresponding longitudinal adjustment of said conduit and connectedatomiz- 4 ing head relative to said front cap to vary the distancebetween the aligned apertured wall of said front cap and fuel dichargeorifice, the apertured wall intercepting a varying portion of the fuelspray discharged from said orifice prior to ignition, and means forcollecting the intercepted fuel spray and returning the same to saidoutlet compartment.

2. A liquid fuel burner comprising an elongated housing having opposedfront and rear open end portions, a conduit forming a fuel passagespatially disposed in and extending longitudinally of said housing, saidhousing and conduit being connected for relative movement, bearing meanssupporting said conduit within said housing and dividing said housinginto a fuel inlet compartment and a fuel outlet compartment, saidhousing having a fuel inlet communicating with said inlet compartmentand a fuel outlet in communication with said outlet compartment, saidconduit having an opening in communication with said fuel inletcompartment, an atomizing head connected to the discharge end of saidconduit, said head including means defining a fuel whirl chamber havingan orifice for discharging fuel therefrom in the form of a spray, a capmember having an aperture therein connected to the housing to close theinner end thereof, said apertured cap member being spaced from saidatomizing head with the aperture therein being substantially in coaxialalignment with said orifice, and means for adjusting said conduitaxially of said housing, said adjusting means including a rotatable rearcap on the rear end of the housing, and a spring means normally biasingsaid conduit in engagement with said rear cap so that rotation of saidrear cap provides for a corresponding longitudinal adjustment of saidconduit relative to said housing to vary the distance between saiddischarge orifice and aligned aperture, so that a variable portion ofthe fuel spray is intercepted upon discharge from said orifice, prior toignition, and means for collecting the intercepted fuel spray andreturning the same to said outlet compartment, said latter meansincluding a passageway defined by said cap member and atomizing head.

3. A liquid fuel burner comprising an elongated housing having opposedfront and rear open end portions, a conduit forming a fuel passageway,said conduit being disposed in and extended longitudinally of saidhousing, heating means for slidably supporting said conduit within saidhousing for movement relative to one another, said bearing meansdividing said housing into a fuel inlet compartment and a fuel outletcompartment, said housing having a fuel inlet connecting with said inletcompart ment and a fuel outlet connecting with said outlet compartment,said conduit having an opening in communication with said fuel inletcompartment, an atomizing head connected to the discharge end of saidconduit, a flanged plug means sealing the other end of said conduit,said atomizing head including means defining a fuel whirl chamber havingan orifice for discharging fuel therefrom in the form of a spray, a capmember having an aperture therein connected to the housing to enclosethe front end portion of said housing with the aperture thereof being insubstantially co-axial alignment with said orifice, and means foradjusting said conduit axially of said housing for varying the distancebetween said orifice and aligned aperture, said adjusting meansincluding a rotatable rear cap threaded to the rear end of said housing,a coil spring concentrically disposed about said conduit and inengagement with the flanged plug thereof for normally biasing saidconduit in engagement with said adjusting rear cap so that rotation ofsaid rear cap provides for a corresponding longitudinal adjustment ofsaid conduit relative to said housing for varying the distance between:said orifice and aligned aperture whereby a variable outer peripheralportion of the fuel spray is intercepted by said apertured cap upondischarge from said orifices prior to ignition, means connected to saidadjusting rear cap to provide for vernier adjustments, said latter meansincluding a stud threaded into the end of the adjusting rear cap, saidstud being disposed in axial alignment with and in engagement with theflanged plug of said conduit for finely adjusting said conduit withinsaid housing.

4. A liquid fuel burner comprising a housing, a conduit forming a fluidpassage extending into said housing, means for supplying a liquid fuelto said conduit from a suitable source of supply, an atomizing headconnected to the discharge end of said conduit, said atomizing headincluding an orifice through which liquid fuel is discharged as a spray,means connected to the end of said housing for intercepting a portion ofthe dispersement of said spray, means for moving said atomizing headaxially relative to said spray intercepting means through the actuationof said conduit connected to said head whereby relative movementtherebetween varies the amount of spray dispersement intercepted by saidspray intercepting means and the angle of the unintereepted portion ofsaid spray, and said intercepting means and atomizing head beingdisposed in spaced relationship to one another to define within saidhousing a return flow passageway for the intercepted portion of thefuel.

5. A liquid fuel burner comprising an elongated housing having opposedfront and rear open end portions, a conduit forming a fuel passagespatially disposed in and extending longitudinally of said housing,means for connecting said housing and conduit for relative movement withrespect to one another, bearing means supporting said conduit withinsaid housing and dividing said housing into a fuel inlet compartment anda fuel outlet compartment, said housing having a fuel inlet openingcommunieating with said inlet compartment and a fuel outlet opening incommunication with said outlet compartment, said conduit having anopening in communication with said fuel inlet compartment, an atomizinghead connected to the discharge end of said conduit, said head includingmeans defining a fuel whirl chamber having an orifice for dischargingthe fuel therefrom in the form of a spray, a cap member having anaperture therein, said cap being connected to the housing to close thefront end thereof, whereby said apertured cap member is adapted tointercept a portion of said fuel spray before ignition, said cap memberand atomizer head defining therebetween a return flow passageway forreturning the intercepted portion of the fuel spray to said fuel outletcompartment, and adjusting means connected to the rear end of thehousing, said adjusting means providing for external longitudinaladjustment ofsaid conduit relative to said housing during burneroperation to vary the axial distance between the orifice and saidintercepting apertured cap member to control the portion of the fuelspray introduced into a combustion space.

References Cited in the file of this patent UNITED STATES PATENTS2,177,781 Haynes et a1 Oct. 31, 1939 2,613,112 Fletcher Oct. 7, 19522,736,608 Martin Feb. 28, 1956 2,873,099 Witlke Feb. 10, 1959 FOREIGNPATENTS 761,823 France Ian. 13, 1934 39,654/57 Great Britain Dec. 20,1957 454,522 Belgian Dec. 19, 1958 234,405 Holland Dec. 19, 1958 27/80Italy Dec. 16, 1958 44,346/58 Austrailia Dec. 17, 1958 66,158/58 IndiaDec. 17, 1958

